Legislators, lobbyists and other interested parties gather Feb. 2 under the dome at the State House in Augusta. The Maine Ethics Commission on Thursday unanimously endorsed stricter disclosure rules for out-of-state donors to Maine campaigns. The proposal will go to the Legislature.

AUGUSTA, Maine — Among the issues to be considered by the Legislature in the coming months will be identifying the source of millions of dollars that flows into Maine’s elections from outside groups, after a unanimous vote Thursday by the state’s campaign finance watchdog.

The Maine Ethics Commission voted 5-0 in favor of a proposal that would require groups that donate more than $100,000 to a campaign in Maine to disclose information about themselves, including what kind of organization they are and their top five donors. The new legislation would apply to out-of-state organizations that contribute to Maine political action committees, party committees and ballot question committees.

Under current law, the organizations in question are listed as contributors to Maine groups but are not required to file any paperwork to the state.

The proposal comes as the amount of money flowing into Maine politics climbs a steep incline. In 2009, the National Organization for Marriage contributed more than $2 million to a political action committee called Stand for Marriage Maine, which supported a successful citizen-initiated repeal of a John Baldacci-era same-sex marriage law.

The tide of money into Maine has continued. In 2016, at least 13 organizations contributed more than $100,000 to Maine’s elections. The ethics commission staff floated a similar proposal in 2015, but it was rejected by the commission. On Thursday, the board’s attitude was much different.

“People want to know where this money is coming from and who’s behind it,” said Commission Chairwoman Margaret Matheson, an independent from Augusta. “But I also want to be respectful to the fact that we don’t want to be enacting something that won’t at least pass constitutional muster.”

Republican Commissioner Richard Nass of Acton said he thinks Mainers want more transparency in elections, particularly after this year’s ballot with its five citizen-initiated referendums.

“My sense is that enough folks are sick of what’s happening with the referendums now that it’s worth a discussion in the Legislature,” said Nass. “I think part of our job as a commission is to get these thoughts over there [to the Legislature].”

Democratic Commissioner William Lee III of Waterville said the proposed disclosure requirements shouldn’t be cause for concern among political donors.

“I don’t find this to be unduly infringing upon someone’s First Amendment rights to have them make this one-time filing,” he said.

The legislation will be considered by the 128th Legislature, which was sworn into office on Wednesday and returns to begin consideration of bills in January.